"""Shared FastAPI dependencies.

The :class:`ServiceState` and :class:`SyncConfig` are created once in
``service.run`` and injected into routes via ``Depends``, avoiding global
singletons. Routes get a ready-to-use :class:`HealthChecker` rather than the
raw state, so each endpoint declares only what it needs.
"""
from __future__ import annotations

from fastapi import Depends

from ..config import SyncConfig
from ..health import HealthChecker, ServiceState

# Bound at app creation time (create_app). Module-level holders are acceptable
# here because there is exactly one app per process and they are write-once.
_state: ServiceState | None = None
_cfg: SyncConfig | None = None


def bind(state: ServiceState, cfg: SyncConfig) -> None:
    """Stash the singletons for the lifetime of this app (called once)."""
    global _state, _cfg
    _state = state
    _cfg = cfg


def get_state() -> ServiceState:
    assert _state is not None, "ServiceState not bound -- call bind() first"
    return _state


def get_config() -> SyncConfig:
    assert _cfg is not None, "SyncConfig not bound -- call bind() first"
    return _cfg


def get_checker(
    state: ServiceState = Depends(get_state),
    cfg: SyncConfig = Depends(get_config),
) -> HealthChecker:
    return HealthChecker(state, cfg)